package com.google.code.mochaccino.framework.crypto.cipher;

/*
 * Copyright 2012 Claude Houle claude.houle@gmail.com
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.GeneralSecurityException;
import javax.crypto.Cipher;
import org.apache.commons.io.IOUtils;

/** Do Final block-based implementation */
public class CipherHandlerBlockDoFinal extends CipherHandlerBlock {

	/** Constructor */
	public CipherHandlerBlockDoFinal() {
		super( 16 );
	}

	/** Constructor */
	public CipherHandlerBlockDoFinal( int defaultBlockSize ) {
		super( defaultBlockSize );
	}

	@Override
	public byte[] transform( Cipher cipher, byte[] data ) throws GeneralSecurityException, IOException {
		ByteArrayOutputStream out = new ByteArrayOutputStream( cipher.getOutputSize( data.length ) );
		transform( cipher, new ByteArrayInputStream( data ), out );
		return out.toByteArray();
	}

	@Override
	public void transform( Cipher cipher, InputStream in, OutputStream out ) throws GeneralSecurityException, IOException {
		int blockSize = getBlockSize( cipher );
		if ( blockSize == 0 ) {
			out.write( cipher.doFinal( IOUtils.toByteArray( in ) ) );
			return;
		}

		byte[] block = new byte[blockSize];
		int byteRead = -1;
		while ( (byteRead = in.read( block )) != -1 ) {
			byte[] chunk = cipher.doFinal( block, 0, byteRead );
			if ( chunk != null && chunk.length > 0 ) {
				out.write( chunk );
			}
		}
		out.flush();
	}
}
